Chen et al. (2026): Direct air capture enabled by low-grade thermal energy via hot water regeneration of a ligand-exchange sorbent

Hao Chen, Xinkai Wu, Haibo Liu, Hang Dong and Arup K. SenGupta, IN: Chemical Engineering Journal, https://doi.org/10.1016/j.cej.2026.174640

Direct air capture (DAC) offers a geographically flexible pathway toward negative emissions, yet its large-scale deployment remains constrained by the high energy demand and operational complexity of sorbent regeneration. While substantial effort has focused on lowering regeneration temperatures, most existing DAC systems remain poorly matched to the largest and most underutilized fraction of industrial waste heat: low-grade (<100 °C) liquid heat streams, such as hot water. This mismatch arises because conventional sorbents are primarily designed for gas-phase or dry-state regeneration. Such processes often require vacuum operation, inert sweep gases, or repeated dehydration-rehydration cycles. Here, the authors systematically evaluate a direct liquid-phase DAC regeneration strategy enabled by a hybrid polymeric ligand exchanger (Poly-LigEx-Cu²⁺), specifically designed to operate under hydrothermal conditions at ambient pressure.

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